Field of the Invention
The present invention relates to boron/nitrogen co-doped graphene for semiconductor applications and a method for producing the same.
Description of the Related Art
Carbon materials, such as fullerenes, carbon nanotubes, graphene, and graphite composed of carbon atoms have attracted increasing attention in recent years.
Particularly, research on carbon nanotubes and graphene is actively underway. Graphene can be formed on a large area and possesses high conductivity as well as good electrical, mechanical and chemical stability. Due to these advantages, graphene is gaining particular interest as a basic material for electronic circuits.
Graphene is a basic building block for graphite and is a thin film whose thickness corresponds to that of one carbon atom.
Graphene is a two-dimensional planar material consisting of covalently bonded carbon atoms in a hexagonal arrangement. Graphene has excellent physicochemical properties, a specific surface area as large as about 2,000-3,000 cm2/g, and superior thermal and electrical conductivity.
Graphene production processes can be broadly classified into two approaches: bottom up and top down processes. According to a representative bottom up process, graphene is synthesized by chemical vapor deposition and epitaxy of a carbon precursor on a suitable substrate, such as a metal or silicon substrate. This process enables the synthesis of high-quality graphene depending on reaction conditions but requires high temperatures for graphene synthesis. Another problem is that the yield of graphene is limited depending on the area of the substrate used.
Meanwhile, according to a representative top down process, planar graphite is oxidized, a sheet of graphene is exfoliated from the oxidized graphite, and the graphene oxide is reduced. This oxidation/reduction process uses a strong acid for the oxidation and a strong reducing agent for the reduction. However, the graphene structure damaged by the oxidation is not fully recovered to its original state even after the reduction. Other examples of top down processes for graphene production include edge exfoliation and ball milling. According to the edge exfoliation process, edges of graphene sheets constituting graphite are selectively functionalized, followed by exfoliation. According to the ball milling process, graphene is isolated from graphite by mechanical exfoliation.
Graphene doping processes can be divided into physical doping and chemical doping. Physical doping is based on physical binding between graphene and doping agents and is thus susceptible to external environmental factors. This susceptibility makes it difficult to continuously maintain the doping effects. In contrast, chemical doping is based on chemical bonding between dissimilar elements and graphene and is thus advantageous in continuously maintaining the doping effects. The physical properties of graphene vary depending on the characteristics of dissimilar elements introduced into graphene and can thus be controlled as desired by varying the amounts and kinds of the dissimilar elements.
On the other hand, graphene produced by the bottom-up or top-down process is a semi-metallic material with high electron mobility. However, the graphene cannot be applied to semiconductors for on/off control in logic elements due to the absence of band gap therein. Thus, there is a continued need for research aimed at finding available graphene for semiconductor applications based on chemical doping. Despite this, such research is in its infancy.
As the prior art, Korean Patent Publication No. 10-2011-0016287 (“Patent Document 1”) relates to a method for coating with graphene oxide. Specifically, a colloidal graphene oxide solution is directly coated on the surfaces of various bases, dried, and thermally processed to form graphene thin films on the bases. However, Patent Document 1 neither discloses nor suggests a technique associated with the use of graphene in semiconductor applications by forming a band gap in the graphene.